1. Field of the Invention
The present invention relates to lipid derivatives which may be used as PAF (Platelet Activating Factor) antagonist or antitumor agent in the field of medicine.
In more detail, the invention relates to the compounds represented by the following formula (I). ##STR2## wherein R.sub.1 is alkyl or alkylcarbamoyl; R.sub.2 is lower alkyloxy, lower alkylcarbamoyloxy, lower alkylcarbonylamino, lower alkyloxycarbonylamino, lower alkylureido, lower alkyloxymethyl, lower alkylcarbonylmethyl, cyanomethyl, heterocyclic group, or heterocyclyloxy; R.sub.2 ' is hydrogen or taken together with R.sub.2 forms --O(CH.sub.2).sub.m -- wherein m is an integer of 1 to 5; R.sub.3, R.sub.4, and R.sub.5 each is hydrogen or lower alkyl or two or three of R.sub.3, R.sub.4, and R.sub.5 taken together with the adjacent nitrogen atom form cyclic ammonio; R.sub.6 is hydrogen or lower alkylcarbonyl; X.sup.- is a counter anion; Y is oxygen or sulfur; and n is an integer of 1 to 10.
2. Prior Art
PAF which is represented by the following formula: ##STR3## wherein m indicates 16 or 18 is generated from basocyte, neutrophile, acidocyte, macrophage, mast cell, platelet, human leukemia cell, or vascular endothelial cell through various stimulations.
In addition to the platelet activating action, PAF has been known to have the biological activities such as constriction of smooth muscle, decrease of coronary blood flow, inhibition of cardiac effect, increase of vascular permeability or hypotension. It is thought that PAF plays an important role in some physiological and pathological reaction, such as inflammation, asthma, thrombosis, anaphylactic shock, allergy, hypotension, ischemic heart disease, acute transplant rejection, nephritis, and gastric ulcer.
PAF antagonists are being developed as agents for the treatment of those diseases. [P. Braquet et al., Pharmacological Reviews, 39, 98-145, (1987)]. Some PAF antagonists which are structurally analogous to PAF are disclosed, for example, in JPN Kokai Nos. 57-67589, 60-243047, and 62-228088.